This shouldn't surprise you much. Trump's strategy in Syria has been pro rebels since the beginning of this presidency. He has enough things to worry about so at the moment it's smart to handle critical stuff first and just basically ignore Syria(or in this case follow the past admin's narrative)
I'm sure he knows very well what's going on in there, but if he suddenly decided to make big moves in there(for example start supporting Assad) it would get a lot of media attention and just create yet another unnecessary distraction for him.
You don't want to deplete your resources by creating multiple battlefronts.